From Supreme Commander Wiki
The Cybran T1 Assault Bot, nicknamed the Mantis, is a Cybran unit. This is a direct fire unit.
The Mantis is Cybran's Heavy T1 unit. It has legs, thus is termed a 'bot'. However, the Mantis serves the role of a medium tank in Cybran army. It has average HP and is armed with a Light Pulse Laser.
The Mantis is a quick-accelerating and fast-moving heavy T1 unit, making it the most maneuverable of the four. This unit also posses the highest ROF among the four, helping to reduce lost DPS to missed shots. However, the overall DPS is less than the Aurora, and the initial shot damage is lower than the Striker's. Combine with the lowest weapon range and the highest build cost, the Mantis is the least effective combat unit in terms of 1-on-1 combat engagements. The Mantis, however, can overcome this disadvantage through tactical and strategic maneuvering to ensure opposition is always met in lesser numbers, thus creating a higher probability of favorable outcome, and the Mantis can quickly retreat from any situation that may become unfavorable, an ability the other three Heavy T1 units do not possess.
Also, the Mantis possesses an engineering suite, allowing it to assist buildings and repair allied units at 1/5th the rate of a T1 engineer. A large group of Mantises can increase the build rate of any structure or unit substantially. Despite having an engineering suite, it can not be ordered to reclaim units, unlike the Aeon's Harbinger.